Abstract

Every year a greater need for accurate analysis of
the size distribution of subsieve material is being
felt by the engineer, because of the increasingly vital
part it plays in the manufacture of cement, pigments, and
other powdered products. Sieves are a satisfactory means
of obtaining this information as long as the material is relatively coarse, but when from 70 to 95 per cent of the sample passes the 200-mesh screen (the finest one giving consistent reading), some new scheme of analysis must be used.
Several methods of analyzing this fine fraction have
been developed. For example, Professor Work at
Columbia has perfected an excellent microscope technic.
Elutriation and sedimentation methods employing various
fluid media have been shown to be feasible, and
additional methods are constantly being developed, but
most of them are slow and tedious.